Wood checkering machine



May 12, 1959 J. CROWE woon CHECKERING MACHINE 6 Sheets-Sheet 1 FiledMarch 5, 1957 INVENTOR.

CR'OWE N H O J May 12, 1959 J. CROWE 2,886,078

' wooo CHECKERING MACHINE Filed March 5, 19's s Sheets-Sheet 3 IN V ENTOR.

JOHN CROWE BY f w J. cRowE woon CHECKERING MACHINE 4 E q o 5 W E m 0 i mR M, W C I o N 2 5 W (M a J \A ,v I D III m L 1 A 2. Q? D 2 (M y 9 N uhuh km. m E 3,

May 12, 1959 Filed March 5, 1957 J. CROWE wooo CHECKERING MACHINE May12, 1959 6 Sheets-Sheet 4 'Filed March 5, 1957 W V F FIG-ll INVENTOR.

JOHN CROWE May 12, 1959 J. CROWE 2,386,073

' 4 WOOD CHECKERING MACHINE Filed March 5, 1957 s Sheets-Sheet sINVENTOR.

JOHN CROWE y 1959 J. cRowE 2,886,078

- WOOD CHECKERING MACHINE Filed March 5, 1957 6 Sheets-Sheet 6 WORK AREANO-I FIG l6 WORK AREA NO2' B FIG-l7 ELECTRICAL CONTACT CAM I35 5FOLLOWER SELECTOR SWITCH I43 |e7 V I66 I ELECTRICAL CONTACT CAM I34 axFOLLOWER 142 r IRETURN STROKE C 3 Y SWITCH ma MAIN MOTOR SHUT DowNSWlTCH l63 Y Fl G [5 INVENTOR.

JOHN CROWE z M M United States Patent '0 2,886,078 a WOOD CHECKERINGMACHINE John Crowe, St. Joseph, M0,, assignor to Olin Mathieson ChemicalCorporation, a corporation of Virginia Application March 5, 1957, SerialNo. 644,941 9 Claims. ((31. 144136) The present invention relates tocheckering machines and in particular to automatic checkering machinesadapted to checker gun stocks. The invention also relates to a processpracticed by the operation of the ma; chine.

It is a particular object of the invention to provide an automaticmachine adapted to receive a wooden or plastic work piece such as aforearm of a rifle or shotgun and to perform a cutting operation thereonin accordance with a predetermined pattern.

A particular object of the present invention is the provision of amachine adapted to receive a work piece and to carve at least twoindependent and separate areas thereof in automatic fashion and insequence without any manipulation by anoperator.

A further object of the invention is 'to provide a machine of the abovegeneral character which, when set in motion, will accomplish insequential fashion a variety of operations and which, upon thecompletion of the operations, will automatically shut down. r

It is astill further object of the present invention to provide amachinefwhose operation involves the practice of a novel process. i i

In general, a machine embodying certain principles of the presentinvention may include an arbor for supporting a work piece such as awalnut forearm of a gun stock and a circular milling cutter mountedadjacent the work piece and adapted to mill grooves therein. Means areprovided for rotating and reciprocating the work piece with respect tothe milling cutter so that, in effect, the cutter may be said to begenerating a thread having a predetermined angle of lead. Since the workis rotated or oscillated through a predetermined arc while it isreciprocated axially, the cutter head is held stationary whileaccomplishing a single cut.

Automatic means are also provided for reversing the rotation of the workpiece and for changing the angular position of the cutter head. Thisaction is effective to cut grooves or threads, initially, with aHlefthand lead and thereafter with a right hand lead or vice versa. In thisfashion, a knurled effect, known as checkering, is achieved on thesurface of the work piece. In effect, a plurality of small raisedportions having a diamond or pyramid shape are created.

Meansare also provided for controllingthe cutter whereby the cutter maybe moved away from the work during certain intervals and thereaftermoved towards the work so that the checkering falls withinapredetermined area to define a desired pattern. t

As stated previously, the work piece is oscillated through apredetermined arc while it is reciprocated. Thus, if for the interval ofeach cut, one were to assume that the milling cutter mounting remainsstationary, it is readily apparent that a single groove or thread willbe milled inthe work piece as the work is oscillated and reciprocatedsimultaneously. It is tobeflunderstood that to accomplish a given out inthe work piece, it is necessary for the work piece to rotate first in ar 2,886,078 Patented May 12, 1959 the work piece, the cutter beingraised away from the work during return strokes.

Aftereach single out has been accomplished, means are provided forindexing the milling cutter head a predetermined distance along the workpiece to provide new surface for milling a new thread.

After all cuts have been accomplished (having a lefthand or right-handlead as the case may be) the milling cutter is shifted automatically toa new angular position with respect to the work and the oscillatorycycle of the work piece is reversed correspondingly so that there afterthreads or grooves of the opposite hand are milled. Means are providedfor indexing the cutter in both axial directions so that the cutterfirst is indexed from left to right as vieWedinFig. 1 to make the firstseries of cuts of one hand and thereafter indexed from right to left tomake the cuts of the opposite hand.

Usually a forearm is checkered in accordance with a desired pattern onopposite sides.- Accordingly, means are provided by the presentinvention for rotating the work piece automatically when a first side iscompleted to present the opposite side of the work piece to the millingcutter. "Thereafter the general operation just described is repeatedautomatically.

Ultimately when both sides oftthe work piece are completed, a countermeans is effective toshut down the machine whereupon the operator mayremove the finished work piece and recharge the machine.

The cutting head is also provided with a novel means for assuringuniformity of depth of grooves through- .out the full checkering patternin spite of variations or tion will becomemore apparent from anexamination of the succeeding specification and drawings, in which:

Fig. l is a perspective view of the complete machine;

Fig. 2 is a perspective view of thecutting head assembly; r I

Fig. 3 shows a, trigger and latch mechanism utilized to cast the cuttinghead from a right hand thread cutting position to a left handthreadlcutting position and vice versa; I i

Fig. 4 shows a flip-over or gear change device utilized to change thedirection of rotation of the Work piece;

Fig. 5 is a perspective view of the cutting head indexingmechanism withcertain portions thereof broken away; I

Fig. 6 is a view of the portion of the showing of Fig. 5 illustratingthe'elements utilized to engage and disengage the indexing pawls;

Fig. 7. is also a viewof a portion of Fig. 5 showing to advantage thecooperation between the indexing pawls and the driving link therefor;

Fig. 8 is a perspective view of the cutting head yoke including theindexing racks and cam contactor;

Fig. 9 is an explodedview of the clutch mechanism;

Fig. 10 shows the. clutch actuating yoke;

Fig. 11 is a schematic showing of the arrangement of the contact cams,one contact cam being utilized to cut right hand grooves, thework pieceand the other contact cam being utilized to cutthe left hand grooves;

Fig. 12 is a schematic showing of the angle through which thecuttingheadwis rotated when shifting from a right hand groove or thread cuttingposition to the opposite hand or vice versa;

Fig. 13 is ashowing 'ofthe counter device utilized to shut down themachine upon-thecompletion of -a-work piece; this device is mounted uponthe back side of the machine as viewed in Fig. l;

- Fig. 14 is a similar view showing-the-counter 'device in theshutdowncondition.

Fig. is a wiring diagram utilized to control the checkering machine;

Fig. -16 is a schematic showing of therelative positions of the workpiece and the cutting head while checkering is beingaccomplished inworkarea-No. 1;

Fig. 17 is a similar showing of the same elements while checkering isbeing accomplished in work area No. 2; and j Fig. 18 is a verticalsection of aportion of the cutting head of Fig. 2 as viewed in'the planeof'theline 'l8'18.

Referring'now to the drawings and in particular to Figs. lthrough 7,there-isshown a -main-support memher comprising a channel 10. Threemainvertical-supports 11, 12-and 13 are spaced along the channel 10.Supports 11 and 12 define,-in"general, the area'nwithin whichthecheckeringmachineis driven and controlled,

while the area of the-machine between thesupports 12 and 13 is occupiedby'the work piece and the cutting head.

-In the embodiment of the invention illustrated .in Fig. 1, the workpiece is a wooden forearm of'a conventional firearm usually of Walnutand designated here by the reference numeral W.

Referring now in detail to the powerand control area of the machinedefined bythe" vertical supports 'lland 12 and for convenience referredto hereinafter by the reference numeral 14, there is shown a main powersheave 16 connected toa gearbox 17. 'The'gear box supplies power to acrank 18 which, 'in'turn, reciprocates a lever 19. The lever 19reciprocates a primary rack '21 which is in engagement with a gearsector "22.

The gear sector 22 is keyed to and carried by a stub shaft 23 supportedon a vertical web member 24 suitably mounted upon the channel 10. Uponthe opposite side of the web 24a stub shaft 23'carries anothergearsector 26 (shown in dottedlines) in'engagement with a sliding rack 27.It is to be noted that the gear sector26 is generally of the samediameter as the gear sector22; however, the stub shaft 23 also carriesan additional gear sector disposed in thesame vertical plane as thesector 26 but of larger diameter. This latter sector, indicated by thereference numeral 28, is utilized to reciprocate the work piece W fromright to left as viewed in Fig. 1 in a'manner which will become moreapparent hereinafter,

Referring now in detail to Figs. 1 and 4, it is apparent that slidingrack 27 has a projection which engages still another gear sector '29.Sector 29 in turn engages and reciprocates a relatively short rack 31.

The short vertical rack 31 carries aflip-over or gear change 'devicewhich is operable to cause the rack to drive one or the other of a pairof work rotating racks indicated hy the reference numerals 32 and 33.respectively.

Short rack 31 carries a generally triangular-shaped rock lever 34 havingoppositely disposed'arms36 and 37 respectively. The rock" lever 34 ispivotally mounted to the rack 31 by means ofthe pin 35 and'is alsoprovided with a suitable spring pressed detent 38 eifective to encouragethe rock 'lever.to. rock from the "position shown in Fig. 4 wherein therotating rack132 is being driven to a secondpositioncorrespondingto acondition inpwhich, the rack 33 is being driven.

' his to be noted that a cross slide 39 is also mounted in the shortrack and carries a pin 41 which engages a cooperating recess 42 in therock lever. In this manner, whenthe rock lever'34 is'rocked to and froin 'thedirections indicated by 'the arcuate arrow in Fig. 4,'fthe rocklever-by virtue of the cooperation of the'pin41 andthe recess 42 acts tocast the cross slide 39 from the position shown in Fig. 4 whereinthe'tip 43 thereof is in engagement with a notch 44 formed in the rack32 to a position wherein the tip 46 thereof will engage a correspondingnotch 47 formed in the rack 33.

Thus, by virtue of the rock lever and cross slide carried by thereciprocating short rack 31, it is possible to cause the rack 31 todrive the rack 32 or the rack 33, in turn causing gear 58 to revolveclockwise or counterclockwise during the upward stroke of short rack 31.

The manner of accomplishing -flip-over of the'rock lever is as follows:

Asstated before, the rack 31, which carries the rock lever 34 and thecross slide 39, is constantly reciprocated vertically by the gear sector29. The cross slide may be in driving engagement with either the rack 32or the rack 33. It is also to be noted that there is suflicientclearance between the endsof a pair of guide bars 48 (rigidly mountedtozthe web 24 in a manner more apparent in'Fig. 1) to permit the rocklever and the cross "slide'to pass between the ends of the bars 48 andthe face of vertical 'rack slides 49. A block' 51* rigidly mounted tothe bars 48 carries a horizontal shift-lever 52 pivotally mounted to theblockiby a pin 53.

'The shift 'leverisipivotally connected to a timing rod '54 so thatreciprocation of the ,timing rod alongthe path indicated 'bythe arrowsofFig. will operate to rotate the shift lever. When the timing lever iswithdrawn or moved to-the left as'shown in Fig. 4, a projection 56 ofthe shift lever is cast into'the path of the reciprocating rock lever'34such that the arm36 of the lever is engaged bythe projection 56 and'therock lever is cast to the left to the position shown in Fig. 4.

'Correspo'ndingly, the cross slide 39 is cast to the left and the tip43thereoffinds its way'into the notch44 of the rack 32 thus making adriving connection between rack "31 and rack 32. After a predeterminedinterval and in sequentialfashion,-the 'timing rod 54 is automaticallymoved to the right as viewedin Fig. 14 thus placing a projection 57 ofthe shift lever 52 into: blocking ,position with respect to the blockinglug '37 of the rock lever. "When the projection 57'and'the lug 37collide, the rock'lever is castto the right as viewed in'Fig. 4 causingthe tip "46' of the cross slide39 to engage the notch'47' formed in therack=33'. In this manner, power has been withdrawn from the rack;32 andapplied to the rack 33.

Pinion v58, 'driven'for a predetermined interval by the rack32 andthereafter by the'rack 33, constantly oscillates through a predeterminedarc and is carried by a main 'shaft"59 suitably journaled in the support'11. As will be apparent fromthe showing of Fig. l, shaft'59 runs thefull length of the machine and rotates the work piece W through acorresponding arc.

T-hemain shaft 59 is suitably journaled in the support '12. and'in thesupport 13 .andalso carries a pinion 61 adjacent the support12 fordriving a pair of cam "pinions '62 and"63 in a manner whichwill' becomemore apparent hereinafter.

"The shaft '59 carries a sleeve 64 slidably mounted 'thereonand formedon the underside thereof with a rack adapted .to engage the teeth of thelarge gear sector '28. Sincethe gear sector '28 constantlyoscillateswith the stub shaft 23, 'the'sleeve'64 is caused toreciprocate to and'fro' al'origfthe shaft 59 whil'ethe shaft '59 rotatesin oscillatory fashion. The sleeve64 is formed with an undercut grooveor keyway 66 adapted to receive the ,headsi'67 of a pair.'(only oneshown) of elongated'keys "68 slidablyreceived in the shaft 59 as isapparent at'69. It is to be noted that the keys68 are rigidly connectedIto the work W and function to cause the work to reciprocate'iin the-direction shown by the arrows of .Fig. 1 whilethewor k 'is oscillatedthrough'a predetermined I ""fl fhereusjno jamm ng action with respect to'the rethat if the work is moved relative to a stationary cuttingelement, a groove having a predetermined lead or a spiral is milled inthe work piece.

For example, with the cutting head in the position shown in Fig. 1, andwith the flip-over mechanism of Fig. 4 in the condition shown therein,the work piece W is rotated towards and away from the cutting head whileit is moved axially along the axis of rotation so that a groovecorresponding to the groove 61 is milled in the work piece.

Cutting head At this point it may be well to point out that the cuttinghead carries a circular milling cutter and means are provided forcontrolling physical contact of the cutter with respect to the workpiece W so that the depth of cut may thereby be controlled and, too, sothat the cutter is maintained clear of the work during the returnportions of both the oscillatory and reciprocatory strokes.

The means for moving the cutting element into and out of engagement withthe work will now be described. In this connection, a reference to Figs.2, 8 and 18 will be helpful.

Thecutting head indicated generally by the reference numeral 71 ispivotally mounted upon a yoke 72 in turn pivotally mounted upon a plate73. The cutting head 71. isso balanced in the yoke 72 that gravity tendsto pull the left portion thereof, as viewed in Fig. 2, downwardlytowards the work piece W. The plate 73 is secured to a pair of feedracks 74 and 76 as is most apparent in Fig. 8. The racks, slidablyreceived in slots formed in the underside of rigid bar 38, are utilizedto move the cutting head along the work piece in a manner which willbecome more apparent hereinafter.

The forward portion of the cutting head is secured to an armature 79integral with an electromagnet 81. The magnet, when energized, isoperative to pivot the cutting head downwardly to aid gravity and tooppose a leaf spring. element tending to lift the cutting head away fromthe work in a manner which will become more apparent hereinafter.

For assuring the accomplishment of a uniform depth of cut a pair offollowers 83 and 84 are slidably mounted within a bracket 86 which inturn makes a lost motion connection with the cutting head wherein thebracket is pivotally supported by the pin 87. The bracket 86 is urged tomove downwardly relative to the cutting head by a leaf spring 85suitably secured to the cutting head and bearing upon a pin 90 supportedin the bracket 86. A rigid bar 80 secured to the cutting head normallyengages a projection 88a formed on the bracket 86 and is effective tolimit the relative motion between the bracket and the head and thusbetween the cutting element 82 and the followers 83 and 84. The positionof the elements 80 and 88a inFig. 18 represents their normal positionand it is to be noted that normally the cutting element 82 is withdrawnwith respect to the followers 83 and 84. Although the followers normallyride upon the work piece, energization of the magnet .81 will'cause thearmature 79 to pull the cutting head 71 downwardly causing the cuttingelement 82 to pivot about yoke 72. The force exerted by the solenoid issufficient to overcome the tendency of the spring 85 to urge the cuttingelement upwardly with respect to the followers 83 and 84 and as aresult, the cutting element is moved to the dotted line position shownin Fig. 18. In this condition, the

cutting element is free to mill a groove in the work piece and thedepth. of the groove is regulated by the prior set ting of the set screw8812 with respect to a stop 880.

The pair of followers 83 and 84 are slidably disposed in the bracket 86,as stated previously, and are carried by a cross pin 86a in turnsupported by a rotatable pin90.

The axis of rotation of the pin. 90 is co-planar with the vertical planewhich includes thegma'ximum diameter of the cutter. The pivotalmountingof the followers 83 and 84 in conjunction with their ability to slideupwardly and downwardly assures a uniform depth of cut during the,occurrence of variations in surface contour or radius of the work piece.1 i

It is to be understood that the followersactually ride on the work atall times; however, when the solenoid 81 is not energized the cuttingelement remains withdrawn above the lowermost portions of the followerstherefore no cutting occurs even though the cutting element is rotating.Energization of the solenoid merely hauls the cutting element downward apredetermined distance beyond the lowermost portions of the followersand cutting occurs.

v Indexing As stated previously, means are provided for indexing thecutting head in incremental fashion along the workpiece W after each cuthas been completed.

Referring again to Figs. 1, 2, 5 and 8, it is apparent that the cuttinghead slides along a rigid bar 88.wherein feed racks 74 and 76 areprovided with extensions which carry the cutter yoke 72. Feed rack 74 isutilized to index the cutting head from left to right as viewed in Fig.1 while feed rack 76 is utilized to index the cutting head from right toleft. A timing bar is provided for placing one feed rack or the other inoperation and correspondingly rendering the other inoperative insequential fashion. The power for the indexing mechanism is pro-. videdby sliding rack 27 (Fig. 5) wherein one end thereof is provided with across pin 89 straddled by a pair of feed levers 91 and 92.

A reference to Figs. 5, 6 and 7 will make this structure more apparent.Note that the elementsare shown as viewed from the opposite side of theshowing of Fig. 1. j The feed levers are pivotally mounted individuallyto the vertical support 12 as at 93 and each carries a pivr otallymounted pawl or dog 94. Each dog is adapted to engage a correspondingrack and are effective to advance the cutting head a predetermineddistance in one direction or the other, depending upon which dog isengaged, asthe slide rack 27 is reciprocated.

.The dogs. are brought into and out of engagement with theircorresponding racks by a pair of rock levers 96 pivotally mounted to thevertical support 12 and actuated by a timing bar. 97.. Each rock leveris provided with a projection 98 which cooperates with a pin 99formed oneach dog.

As is apparent in Fig. 6, rotation of the rock lever in thejdirectionshown by the arrow will cause the projection 98 to contact the pin 99thereby camming the dog upwardly out of engagement with itscorresponding rack. Both rock levers are generally of the sameconstruction, however, the projections 98 are [formed on opposite sidesthereof so that when the timing bar 97 pivots therock levers, one leveroperates to drop a dog into engagement with its corresponding rack whilethe other lever operates to disengage the opposite .dog from its rack.

- Timing bar 1 As is apparent, a great number of mechanical operatronsoccur automatically in the course of checkering a work pieceutilizingthe machine of the present invenhas a projection thereof in the form ofa rod 54 extending towards vertical support 11. It will be recalled thatthe timing rod 54 was discussed in connection with the operation'ofthe'flip-over mechanism for changing rotation of the workpieces Theconnection between the timing rod 54 and the timing bar 97 isaccomplished through the instrumeutality of the rock levers 96 as w1ll Ibe apparent inFig. 5.

The timing bar contains an elongated slot 101 engaged by a depending lug100 mounted upon the cutting-head. The timingbar andits accompanying rodare shifted in the direction of the arrows shown in Fig. 2 by theengagement of the lug 100 with the corresponding end of the slot I01'asthe cutting head is indexed to its extreme right-hand or left-handpositions as viewed in Fig. l. The timing bar 97 and its. extension 54control 1) the gear change or flip-over mechanism (2) the actuation ofselector switch 143 and (3) the engagement and disengagement of theindexing pawls or dogs Reversal of angular position of 'cutting head Asis apparent in Fig. 12, the cutting head is first disposed with respectto the work piece W in a first angularposition. While in this angularposition, the cutting head is indexed after accomplishing each out alongthe full length of the desired pattern accomplishing a plurality ofparallel cuts. Upon completion of these cuts, the head is automaticallyshifted from a position indicated in Fig. 12 by the reference numeral102 to a position indicated bythe reference numeral 103 and a new seriesof parallel cuts are accomplished making an included angle ofapproximately 55 degrees with respect to the cuts formed by the previousposition 'of the cutter.

Incidentally, it is to be noted that "at the time of occurrence of theshift of the cutter fromposition 102 to 103, the cutting head hasactuated the timing bar to cause the indexing mechanism to shift fromone indexing rack to'the other.

A reference to Figs. 2 and 3 will reveal the mechanism that is utilizedin accomplishing the angular shifting of the cutting head. Fig. 3 is aperspective view of the underside of the head support and for purposesof explanation, the plate member 104 may be considered integral withtheyoke element 72. These members are both pivotal "about the pin 106and are connected by the post 107-. The plate 104 is formed with afinger 108 disposed between a pair of Cooking springs 109. The platealso carries a pair of "oppositely disposed notches lllengageable bycorresponding pivotally mounted triggers 112. As the cutting headassembly approaches an extreme position marking the end of apredetermined group of parallel cuts, a spring housing 113 slidablymounted in.

the bearings 1 14 encounters a stop or an abutment such as the abutment116. Continued indexing of the cutting head causes the spring housing toslide through the'bearings 114 thus compressing the adjacent cockingspring 109 against the finger 108. The plate 104 is held againstrotation about the pin 106 wherein the trigger 112 and the correspondinglug 111 are latched in the manner shown in Fig. 3. 1

Further indexing of the cutting head towards the end of its run movesthe latched trigger 112 towards another abutment such as the abutment117. Up'on contact the dog is unlatched=and the compressed cockingspring 109 operates to rotate (in the direction of the arrow of Fig. 3)the plate 104 including the yoke 72 and the cutting head through anangle of approximately 55 degrees or to the position shown by thereference numeral 104 in Fig. 12. At this time, the opposite triggerandits corresponding'not'ch 111 latch the cutting head firmly inpositi'on. a

It is t' 'o be understood that the abutments 116 and 117 respectivelyare mountedupon the vertical upport 13 arfdthat corresponding'a'bu'trnents are provided upon the Turning the workpiece As statedpreviously, it is frequently desirable to checker a given pattern on onearea of a work piece and thereafter checker the same pattern on theopposite side; consequently, the checkering machine of the presentinvention includes means for automatically turning the work piece W froma first work position to a second work position for the purpose offorming an identical pattern in at least two different areas.

' Referring now to Figs. 1, 9 and 10, it will be apparent that the mainshaft 59 is provided with a clutch indi cated generally by the referencenumeral 118. The clutch comprises a driving element 119, a driven member121 and a locking member 122. An operating yoke 123 is formed with anarcuate portion 124 adapted to engage an undercut portion 126 formed onthe locking member. The yoke is pivotally mounted to the block 51 andcarries a pair of operating arms 127 having cam surfaces 128 formedonthe undersides thereof and engagerespect to the driving member 119wherein the lugs 131 are moved beyond driving surface 132.

During the moment of disengagement, a' suitable coil spring (not shown)is free to cause the driven member 121 and locking member 122 to rotateor to be phased approximately 180 degrees with respect to the drivingmember whereby the lugs 131 encounter stops 133. The stops limit thephasing to 180 degrees.

During this occurrence the timing bar 97 hasbeen actuated by the lug(Fig. 2) depending from the cutting head to cause the indexing to bereversed so that upon the next stroke of the slide rack 27 the follower129 moves away from the cam surface 128 permitting the yoke to returnthe locking element 122 into a driving connection with the drivingelement 119.

A second predetermined work area,.namely, the opposite side -of the workpiece W having been presented to the cutting head, the machineautomatically begins to perflgrm cutting operations upon this new areaof the wor A more detailed explanation of the sequence cuttingoperations will be presented hereinafter.

Electrical control cams As stated earlier, electrical means are providedfor controlling the checkering pattern. This is accomplished by sendingan electrical signal to the cutting head solenoid which is eifective tocause the solenoid to pull the cutting element into the work at apredetermined time interval permitting the cutting element tomill agroove of predetermined length as the 'work is rotated and oscillatedand thereafter the signal operates. to dee-n'ergize the cutting headsolenoid effective to terminate cutting, thereby limiting the length ofgroove'and permitting the work to accomplish its return stroke withoutengaging the cutter.

Obviously, the parallel grooves formed while the cutting head is in theposition represented by the reference numeral 103 in Fig; 12 and thoseof the opposite band formed when the cutting head "is in the positiondesignated by the reference numeral 102 inFig; '12 must be con-trolledso that'the ultimate configuration or outline of checker-lug fallswithin a predetermined are'a.

For example, a pattern on work piece W shown in Figs.

7 l and 12 is representative of such an outline.

In order to control the cutting element and the cutting head toaccomplish the desired pattern, four contact cams are provided.

For reasons that will become more apparent hereinafter the electricalcontact cams are provided in pairs,

one pair effective to control the grooves formed while the cutting headis in the position represented by the reference numeral 102 and theother pair eifective to control the grooves milled when the cutting headis in the position represented by the reference numeral 103 of Fig. 12.e p

Referring now to Figs. 1, 8, 11 and 12, the pairs of contact cams aredesignated by the reference numerals 134 and 135 mounted on shafts 136and 137 respectively in turn supported for rotation in the verticalsupports 11 and 12.

It is noted that the shafts carry pinions 62 and 63 in drivingengagement with main shaft pinion 61.

Since the function and structure of each pair of cams is substantiallyidentical, the structure and operation of only one pair thereof will bedescribed in detail, it being specifically understood that one pair ofcams is utilized whenever the cutting head is in the angular positionrepresented by the reference numeral 102 while the other pair of cams isutilized when the cutting head is in the 103 position.

It is noted that each pair of cams take the form of a split cylinder andin the case of contact cams 135 comprising an arcuate electrical contactof brass or copper 138 and another, referenced 139. Current is passedthrough these contact cams to a contactor 141, in the case of pair 135,and 142, in the case of pair 136 (Fig. 8), in a manner which will becomemore apparent hereinafter. The cams are in circuit with the solenoid 81which controls cutting head. The configuration or outline of each cam isformed in accordance with the pattern desired to be cut upon the workpiece W. For example, as the work piece is rotated, the contact camswill be rotated whereby the arcuate cam 138 or 139, depending upon thephasing of the work piece W, will sweep past the contactor 141..Whenever the cam surface engages the contactor, current will flow intocutting head solenoids to pull the, cutting element into the work. Whenthe contact cam sweeps past the contactor 141, the circuit is broken andthe cutting head is immediately re leased from the work. t

. It is to be noted that the contactors 141 and 142 are mounted upon thefeed rack; consequently, they are in dexed along the contact cams,simultaneously with the indexing of the cutting head. r

Pairs of contact cams (such as the segments 138 and 139) of generallyidentical configuration are provided on each shaft 136 or 137 so thatwhen the work piece is rotated from the first work area to the secondwork area as described under that portion of the specification entitledTurning the Work Piece above, a contactscam will be available forcontrolling the cutting head in each position of the work piece. Asstated before, the pair of contact cams individual to a given shaftcontrol the cutting head while in a given angular position such asrepresented by the reference numeral 102 while the other pair, ofelectrical contact camscontrol the cutting head while in the oppositeangular positiondesignated by the reference numeral 103.. l 1

Current is provided to the contact cams by means .of conventional brushand commutator arrangements mountedonthe shafts 136 and 137. A cut outswitch is provided for breaking the electrical circuit to the brushes ina manner which will be more apparent hereinafter.

By the same token, the current flow through a particular pair of contactcams 133 or 134is controlled by a selector switch 143 (see Fig. 1)actuated by the cutting head carriage.

10 Timing Ina typical cycle of operation, the cutting head and the workpiece assume'the following positions in sequential fashion and thecheckering machine correspondingly forms a variety of operationsautomatically. A reference to Figs. 16 and 17 will show schematicallythe sequence of these positions. In Fig. 16 the work piece W is shownpositioned with the first work area presented to the cutting head.Assume that the cutting head is disposed in position A. Operationof thecheckering machine will cause the work piece W to rotate and reciprocateso that a groove ismilled in the work piece in the direction shown bythe arrow. Obviously, the length of the grooves is controlled by theaction of the particular electrical control cams corresponding toposition A. and to work area No. 1, i.e., cam segment 138 of pairs 135.The cutting head will be indexed along the work piece in the directionshown by the horizontal arrow of Figs. 16 until ultimately the finalgroove is milled. Upon completion of the last groove the angularposition of the cutting head will be reversed simultaneously with thereversal of the direction of rotation of the work piece so thatthereafter the cutting head will be in angular position B and thecutting element will begin to mill grooves along the new angularposition; the grooves being milled in the direction shown by the arrow.1

Obviously, when the cutting head is in position B, the control camcorresponding to the angular position and to the particular work area,is in circuit with the cutting head solenoid, i.e., the timing bar 97actuates selector switch 143 to place the proper cam segment of the pairof segments 134 in circuit with the magnet 81.

While in position B the cutting head will be indexed in incrementalfashion along the work piece until ultimately the desired number ofparallel grooves are complete in accordance with the signals controlledby the corresponding electrical contact cam. At this point the clutch isdisengaged by the action of the lug 129 upon the cam surface 128 (seeFig. 10) whereupon the clock spring (not shown) causes phasing orrotation of the work piece through degrees to present work area No. 2,represented by the showing of Fig. 17, to the cutting head. While thework piece is being rotated to work area No. 2, the cutting head isflipped from angular position B to angular position A by the operationof the trigger and latch mechanism of Fig. 3. Furthermore, the directionof rotation of the work piece isalso reversed by the operation of thegear shift device of Fig. 4. Thereafter the work piece W is in theposition shown in Fig. 17 while the cutting head is in angular positionA and the checkering operation proceeds as described in connection withFig. 16. Thereafter and upon completion of the desired number of threadsor grooves from the A position the head shifts automatically to angularposition B; work rotation having been reversed and the series of groovescorresponding to the B position of the cutting head are milled.

Upon completion of work area No. 2, a counter mechanism to be describedhereinafter is effective to shut down the checkering machine whereuponthe work piece may be removed and the machine reloaded.

Counter mechanism Referring now to Figs. 13 and 14, there is shown acounter mechanism comprising a pivotally mounted dog 146 having anoperating arm 147. The dog is pivotally mountedto a bracket 148 in turnsecured to the channel 10. A coil spring 149 urges the dog intoengagement with rotatable lug 151 having a plurality of projections 152,153 and 154. Coil spring 149 constantly urges the dog 146 in thedirection tending to engage lugs 152 and 153. Cooperating with therotatable lug 151 is stop lever 156 having a hook portion 157 adapted toengage projection 154.

When the lug 151 is inthe position shown in Fig. 14 the stop leverrotates in the direction shown by the arrow in response to theurging ofa spring 150 wherein the hook 157 and the projection 154 are engaged.When this rotation occurs, a pin 158 mounted in the upper regions of thestop lever assumes a blocking relationship with respect to a crank arm159 rigidly secured to stub shaft 23 thus blocking further operation ofthe machine.

Simultaneously, the opposite end of the stop lever 156 carrying a pin161 in turn engages a U-shaped switch operating element 162.Consequently, when the stop lever 156 assumes its blocking position theelement 162 is moved to the right as viewed in Fig. 14 with the resultthat a switch 163 operates to open the electrical power circuit to thecheckering machine thus shutting it down.

The counter mechanism is operated by the contact of a lug 164 projectingfrom the underside of the indexing rack 76.

When the cutting head is in position B, the rack 76 is indexedconstantly to the right as viewed in Figs. 13 and 14 until ultimatelythe lug 164 contacts the operating arm 147. When this occurs, the arm147 is rotated in the direction shown by the arrow and the dog slides tothe left and over the lip of lug 152. When the cutting head returns tothe left, spring 149 causes the dog 146 to rotate the lug 151. 1 V

The counter action occurs for the first time upon the completion of workarea No. 1 and corresponding counteraction occurs upon the completion ofwork area No. 2 wherein the dog 146 engages projection 153 to rotate thelug 151 into a position to receive hook 157 into engagement withprojection 154 whereupon switch 163 is opened and operation of themachine is blocked as shown in Fig. 14.

Electrical circuit Referring now to Fig. 15, there is shownschematically the electrical circuits for controlling the operation ofthe checkering machine of the present invention.

Current is supplied from a suitable source of power through the lead 166to the selector switch 143. From the selector switch, depending upon theposition thereof, current flows through electrical cam 135 and follower141 to the junction 167. Of course, if the selector switch is in theopposite position current will flow alternatively through electricalcontact cam 134 and follower 142 to the junction 167. These two currentflow paths correspond to 1) the A and A angular position of the cuttinghead in one case and (2). the B and B angular position thereof in theother case.

In other words, when the cutting head is making grooves from the A or Apositions depending upon which work area is presented to the cuttingelement, current is flowing through the electrical contact 135 andfollower 141 while when the cutting element is making grooves from the Band B' position current flows to the electrical contact cam 134 andcorresponding follower 142.

It is to be understood that when each follower and its corresponding camare in contact, current flows and that when the contour of the cam issuch that there is no physical contact between the two elements, currentdoes not flow in the respective circuits.

From junction 167 current flows through a return stroke switch 168. Thisswitch is located on the main drive sheave 16 and takes the form of acircular commutator segment having a conducting segment of approximately180 and a non-conducting segment through the remaining 180. The angularposition of this commutator is so phased with respect to thereciprocatory and oscillatory rotation of the workpiece W that duringthe return reciprocatory and oscillatory strokes the electrical circuitis broken so that there is the assurance that the cutting head magnetwill be de-energized and the cutting element correspondingly raised outof contact with the work piece.

A reference to Fig. '16 will provide clarification of the function ofthis switch. Assume that the cutting head is in the position A and thatthe: corresponding electrical contact cam and follower having. come intophysical contact. The cutting head will be pulled into the work and agroove will be milled in the direction of the arrow as work piece W isreciprocated from left to right and rotated towards the cutting element.When the reciprocatory stroke has been completed to the left and therotational stroke has been completed in a direction toward the cuttingelement, the work piece traverses return strokes to the starting point.It is during this latter interval, corresponding to the return strokesand actual indexing of the cutter that current to the cutting headsolenoid 81 is divered by the return stroke switch 168, thus assuringthat the cutting element remains raised out of contact with the workpiece.

From the return stroke switch, current flows through the shut downswitch 163 normally in a closed position until the counter mechanismoperates to break the circuit in a manner previously described.Thereafter currentflows through the winding of the cutting head solenoid81 and thence back to the other side of the line.

It is to be understood that the cutting head motor is energized by aseparate circuit and the cutting head motor is maintained in operationconstantly.

Loading and unloading the work piece The work piece W is inserted in thecheckering machine by dropping the upper portion 171 of the verticalsupport 13 about hinge pin 172 in the direction shown by the arrow ofFig. l. Thereafter the work piece is removed from the shaft 59 bysliding it axially along the shaft to the right. A new and uncheckeredpiece may thereafter be inserted by performing the above steps inreverse. It is noted that the shaft 59 in the area where the work pieceis reversed is formed with an arbor having the general configuration ofthe interior of the work piece, thus assuring that the work piece isadequately keyed against relative rotation with respect to the shafts.

Operation Assume that the checkering machine has been loaded with a workpiece W and that the cutting head is disposed in position A ready tobegin checkering work area No. 1 as shown in Fig. 16. Prior to startingthe machine it is necessary to disengage the clutch and wind the clutchspring manually so that upon completion of work area No. 1, the shaft 59will be automatically phased through 180 with respect to the drivingshaft.

It is also necessary to set the counter mechanism in the position shownin Fig. 13.

Thereafter the machine may be set in operation by suitably driving thesheave 16 whereupon the work piece W will begin to reciprocate and torotate in oscillatory fashion. As the work piece rotates toward therotating cutting element and moves to the left as viewed in Fig.

16, contact 141 also begins to scan cam segment 138 of the pair of cams135. When physical contact between these two elements occurs, currentflows to the cutting head solenoid 81 causing the cutting element to bepulled into the work piece. When the length of cut is signaled by thebreaking of physical contact between the elements 141 and 138, thecutting element is withdrawn from the work and the work piece continuesto rotate towards the cutting head and to reciprocate to the left anduntil the ends of the respective strokes are reached.

At this instant, return stroke switch 168 becomes operative to open theelectrical circuit to magnet 81 and the circuit remains open during thecomplete return stroke of the work piece in spite of the fact thatcontact 141 will physically sweep over cam-segment 138 in the course ofthe return stroke.

As soon as the first cut is complete, the appropriate feedv rack andpawl, such as the rack 76 and the pawl 94,

are operative in response to slide rack 27 to index the into position Ain the first instance.

cutting head a predetermined distance along the work piece. Theappropriate driving rack has been placed in driving condition, by theoperation of the timing .bar 97 in conjunction with rock levers 96, thetiming bar, of course, having been set by the engagement of the lug 100with the 'end of the slot 1 01 asthe cuttinghead' swung The cuttinghead] is indexed alongthe work piece in incremental fashion until allgrooves have been milled from position A. I This occurrence is signaledby the engagement of depending lug 100 with the timing bar,

specifically the opposite [end of slot 101. Correspondingly, the triggerand latch mechanism of Fig.3 are operative to cast the cutting head fromposition A toposition B. During this occurrence the lug 100drives thetiming bar 97 to the left with positive motion and the timing bar, inturn, operatesto (1) actuate the selector switch 143 to place theappropriate cam in circuit (2) actuates the gear change orflip-overmechanism'through the instru- A. Upon the completion of allcuts from the B position,

the cutting head is automatically shifted to the A position; theselector switch shifts the current to the opposite pair of. contact camsegments, the gear change device is actuated to reverse rotation of thework piece, the appropriate end rack is engaged while the other isdisengaged in generally the same fashion as the occurrence of theseevents previously described .witbrespect to the shifting of the cuttinghead from position A to position B. There is, however, oneadditionaloccurrence at this moment; namely, the clutch 118 is actuatedby the lug 129 to permit the work piece to be phased through 180 so asto present work area No. 2 to the cutting head.

Thereafterithe machine proceeds automatically to perform the functionand operation described with respect to Fig. 16.

During the course of the operation of the checkering machine, thecounter mechanism of Figs. 13 and 14 is operative in the mannerpreviously described until ultimately, upon the completion of work areaNo. 2, the

counter mechanism is rendered operative to shut down i the machinethereafter the complete work piece W is removed and a new pieceinserted. Repetition of the above described operations may then beundertaken to checker the new work piece.

It is anticipated that various modifications and arrangements may beundertaken as design considerations and engineering practices maydictate without departing from the spirit and scope of the presentinvention.

What is claimed is:

1. An automatic checkering machine comprising an arbor movably mountedin a frame for supporting a work piece, a cutting head mounted in theframe and movable from a normal position to a cutting position effectiveto cut grooves in the workpiece, means for indexing the cutting headalong the work while in the normal position,

means for rotating and reciprocating the arbor and thus the worksimultaneously with respect to the cutting head so that the cutting headwhile in the cutting position mills grooves of a predetermined hand andangle of lead in the stock, a first control means. operable to move thecutting head from the normal position to the cutting position inaccordance with a predetermined pattern and a second control meansincluding a pair of relatively movable followers cooperating with thecutting head and the surface of the work piece effective to insure auniform depth of out throughout the pattern.

2. An automatic checkering machine comprising an arbor movably mountedin a frame for supporting a work piece, a cutting head mounted in theframe and movable from a normal position to a cutting position to cut aplurality of grooves in the work, means for indexing the cutting, headalong the stock after each groove iscut, means for rotating andreciprocating the work simultaneously with respect to the cutting headso that the cutting head while in the cutting position mills grooves ofa predetermined hand and angle of lead, automatic means controlled bythe indexed position of the cutting head for shifting the cutting headand shifting the motion of the workpiece whereupon grooves of theopposite hand are milled, a first control means operable to move thecutting head from the normal positionto the cutting position inaccordance with a predetermined pattern and a second control meansincluding a pair of relatively movable followers cooperating with thework piece and the cutting head effective to insure a substantiallyuniform depth of out throughout the pattern.

3. An automatic checkering machine comprising a shaft movably mounted ina frame for supporting a work piece, a cutting head movably mounted inthe frame and normally spaced from the work piece, means includinganelectro magnet effective to move the cutting head towards the workpieceinto a cutting position, means for moving the shaft and thus the workwith respect to the cutting head so that the cutting head while in thecutting position mills a groove of a predetermined hand and angle oflead in the stock, electrical control means effective to regulate theelectro magnet so as to control the length and continuity of saidgroove, and mechanical control means mounted upon the cutting head andincluding at least two relatively movable followers engageable with thework piece effective to insure substantially uniform depth of groove.

4 An automatic checkering machinecomprising a frame, a work holderrotatably mounted in the frame and adapted to support a generallycylindrical work piece along its longitudinalaxis, said work holderhaving a first working position and a second working position, acuttinghead movably mounted on the frame, means for reciprocating and forrotating the work piece simultaneously while in said first position,means for positioning the cutting head relative to the work piece sothat while the work piece is rotated and reciprocated in said firstposition a threadof a given hand is milled in the work piece, means forindexing the cutting-head along the work automatically after said threadis milled, automatic means responsive to the indexed position of thehead operable to reverse the direction of rotation of the work piece andto change the position of the cutting head whereby a thread of theopposite hand is milled, cam means including an 'electromagnet effectiveto tilt the cutting head to and fro with respect to the work piece tocontrol the length and continuity of each thread and automatic means forshifting the work piece from said first working position to said secondworkingposition so that a new area of the work piece may be checkered.

5. An automatic checkering machine comprising a frame, a work holderrotatably mounted in the frame and adaptedto support a generallycylindrical work piece along its longitudinal axis, a cutting headmovably mounted on theframe, means for advancing and for rotating thework piece simultaneously, control means for positioning the cuttinghead relative to the work piece so that while the work piece is rotatedand advanced a thread of a given hand is milled in the work piece, meansfor returning the work piece to its starting point, said control meansbeing etfective to tilt the cutting head away from the work piece duringthe return stroke", meansfor indexing the cutting head along the workautomatically after each thread is milled, automatic means responsive tothe indexed position of the head and operable after a predeterminednumber of threads have been milled to reversethe direction of rotationof thework piece and to yhange the position of, the cutting headwherebythreads of the oppesitehand are milled, andjcam means cooperatingwith the control means effective to control the length and continuity ofeach thread of both hands whereby apa-ttern of checkering having apredetermined an n i f m d- A machine for automatically checkering a gunstock comprising a fr ame, a work holder supported in the frarne andadapted to support a gun stock generally along its longitudinal axis, acutting head mounted on the frame, means for moving the cutting headintoengagement the stock, means for rotating and advancing the stoc ksimultaneously while the cutting head is in engagement with, the stockeffective to mill a thread in the kfmeans for indexing the cutting headalong the stock automatically for milling a plurality of said threads,automatic means responsive to'the inderring means for reversing thedirection of said rotation and for changing the position of said cuttinghead whereby threads of the opposite hand are milled, andlcam meansincluding an electromagnet effective to control the interval duringwhichitheicuttmg head is held in engagement with the stock Whilecuttingla given thread, means for turning the'stock automatically uponcompletion of a first checkering operation inatfirst area of the stockto present a new area to the cutting head and counter means responsiveto the indexing mechanism operative automatically to shut downthemachine after said new area has been checkered. i i

.7 A machine for automatically checkering a wooden work piece comprisinga frame, a work holder movably supported in the frame and adapted tosupport the work piece generally along its longitudinal .axis, a cuttinghead mounted on the frame, means for moving the cutting head intoengagement with the work, means for rotating and advancing the worksimultaneously while the cutting head is in engagement with theworkeifective to mill a thread in the stock, means for moving the cuttinghead out of engagement with the work, means for returning thework pieceto its starting point, ratchet means for indexing the cuttingheadalong'the stock automatically for milling a plurality of said threads,automatic means including a timing bar responsive to the indexedposition of the cutting head for reversing the direction of saidrotation and for changing the position of said cutting head wherebythreadsof the opposite hand are milled, and cam means includinganelectromagnet effective to control the interval during whichthe-cutting head is held in engagement with the work while cutting agiven thread, means to the indexing means and'operatiye automatically toshutdown the machineafteiia predetermined number of areas have beencheckered. p 4 E t Y 8. A machine for automatically checkering a gunstock comprising a frame, an arbor carried by the frameformovablysupporting the stock, a cutting head movably mounted in the frameand adapted to cut grooves in the stock, means for moving the stock withrespect tofthe cuttinghead and the cuttinghead relative to the stock sothat the headmills at least two groups of grQOYes therein, each grouphaving a predetermined hand'and angleof lead, control means operable tolimit thelength and continuity of each groove in accordance with apredetermined pattern and at second controlmeans including at leasttworelatively movable followers cooperating with 'thecutting head and thesurface ofthe workpiece effective to insure a uniform depthof cutthroughoutthe pattern. i v i 9. In a wood checkering machine includingfawork holder and alcutting head carrying a cutting element, a deviceformaintaining uniformity of depthof'cut in a :WOIk piece carried by thework holder where cutting occnrs while the work piece and the cuttingelement move relative to one another comprising: a pair of followersmovablymounted upon the cutting head and normally disposed in slidingcontact with the surface of the vwork piece while the cutting elementnormally projects a predetermined distance beyond'the followers into thework, saidlwork piece'having variationsin its surface contourcharacterized by high and low regions, said followers being movablerelative to one another along paths generally normal to the surface ofthe work piece so that both followers remain in contact with the work asthe followers encounter said high and low regions, said predetermineddistance remainingsubstantially constant with 2,543,405 2,573,565,Hailston et all 1 Oct. 30, .1951 2,638,946 McDonald et al'. -May19,

V FOREIGN PATENTS 949,845

France Mar. 7, 1949

